But you need at least an 120 mm exhaust fan and (optional) an 120 mm intake fan, both @7-800 RPM's.
Some time ago I've had an X2 3800+ with Ninja rev.B fanless and an 8800GT with AC S1 fanless but in my P182 I've had one exhaust and one middle intake @800 RPM's. No problems with temps or stability.